Super heater in Boiler

The Super heater Tubes serve to super heat the steam from the steam drum.  Steam from the steam drum is saturated steam.  It may still have droplets of water in it.  This steam is passed through tubes passing through the furnace to heat it.  Superheated steam has very high energy and is used to drive the turbines.

The capacity of a boiler is dependent on the amount of superheated steam it can generate.  Super heater tubes must be able to withstand very high temperature and pressure.  The steam-water ratio is designed such that it does not overheat.    Hence, super heater tubes are one of the most important parts of the boiler. 

Super heaters are classified into

  1. Radiant Super heaters which are placed directly in the furnace
  2. Convectional Super heaters which are placed in the path of the hot gases
  3. Separately fired super heaters are heated by a separate heat source.